The invention relates to a gripping means with a gripper designed to be carried by a link in a conveyor chain guided in a guide channel and running in an endless path, along which actuating elements cause the gripper to close or open in order to grip or release an object, generally a flat object such as a newspaper or the like, the gripping means comprising members permitting the gripper to close, retaining it in closed position and, upon intervention, permitting it to open.
The invention relates to a gripping means constituting a further development of the gripping means described in EPC application No. 86 850 339.2 (Wamac AB).
The gripper described in the foregoing application comprises, as explained more fully therein, two jaws pivotable in relation to each other about a shaft, one of the jaws being provided with a sleeve which forms a bearing for the shaft which carries the other jaw. The shaft has an enlarged section adjacent to and having substantially the same diameter as the sleeve. A helical spring surrounds both the sleeve and the enlarged shaft section, tightly surrounding the parts in unloaded state. One end of the spring is secured to the shaft and the other end is connected to a cam sleeve loosely surrounding the spring. The cam sleeve has a cam which must be carefully directed with respect to the fixed jaw on the gripping means, i.e. the jaw carried by the conveyor chain, to ensure that it is correctly influenced by a stop along the track designed to open the gripping means. The cam is aligned in this desired position by the end of the spring being secured at a suitable angle on the shaft so that the cam shaft will always return to the same angular position after being influenced. In order to secure the end of the spring to the shaft, the free end portion of the shaft may be made conical and a conical pinch fit used to clamp the springs against the conical shaft section. The sleeve is then tightened by means of a central screw against the shaft in axial direction.
Although the assembly work is time-consuming and expensive in the known gripping means, they do have a number of favourable features. However, they have also been found to have a number of drawbacks in practical operation. If normal care is taken during assembly it has been found in practice that a relatively large number of gripping means have to be replaced when an installation is being tested.
More gripping means have subsequently had to be replaced during trial operation.
Of course, by being more careful during assembly, it would be possible to reduce the number of gripping means which must be replaced, but the costs for this are considerable.
Considerable efforts have been made to eliminate these drawbacks, which result in unsatisfactory functioning of the gripping means or the relatively high costs, i.e. the time required to assemble the gripping means.